"We are in contact with the Swedish Embassy, who act as the protecting interest for U.S citizens, who are working with the Ministry of Foreign Affairs to address the case," it said.

"We are also assisting the U.S Department of State closely with regards to the situation. In the meantime we would appreciate Otto’s and his family’s privacy being respected and we hope his release can be secured as soon as possible."

The State Department said it was "aware of media reports" about Warmbier's arrest. However, it had "no further information to share due to privacy considerations," spokesman Mark Toner said.

"The University of Virginia has been in touch with Otto Warmbier’s family and will have no additional comment at this time," the college said in a statement Friday.

KCNA said Warmbier was under investigation for "perpetrating a hostile act against the DPRK after entering it under the guise of tourist for the purpose of bringing down the foundation of its single-minded unity at the tacit connivance of the U.S. government and under its manipulation."